Androscoggin, Kennebec, Oxford and Somerset counties are now in the yellow category under Maine’s COVID-19 school health advisory system.

The system, which is used to make recommendations for learning at Maine schools during the pandemic, takes into account the rate of new cases of coronavirus in each county, as well as their positivity rates.

In Friday’s update, the administration of Governor Janet Mills said all other counties remain green, though Franklin and York counties are being “closely monitored.”

A “green” designation means schools in that county can proceed with all in-person learning; yellow suggests a hybrid model; and red means schools should switch to remote learning only.